This invention relates to an electronic tuner for musical instruments, and more particularly to an electronic tuner for detecting and indicating whether or not the frequency of a sound given forth from a musical instrument is deviated from the standard tuning frequency of the particular musical sound and, if deviated, how much it is deviated.
In general, musical sounds or notes are defined according to frequency, so that the frequency of any particular musical sound or note should not differ with musical instruments. However, it is difficult to maintain the musical instruments in their correctly tuned condition. For example, pianos, guitars (except steel guitars) and the like can be played with correct musical intervals for a certain period of time once they are tuned. On the other hand notes given off, by string instruments such as a violin, a steel guitar, etc. and wind instruments appreciably differ with players.
Accordingly, it is necessary to tune the instruments used in orchestras, brass bands and so on. Tuners are employed for such tuning. Heretofore, various types of tuners have been manufactured and sold and one that has been in relatively wide use is a tuner commercially known under the name of "Strobo CONN", manufactured by Conn Inc. of U.S.A. In this tuner, 12 windows are formed in the surface of a panel and, behind these windows, strobe discs are disposed which are coupled together by means of gears and rotate in predetermined ratios to one another. And these strobo discs are positioned so that they can be partly seen through the windows, respectively. One surface of each strobe disc has formed thereon black and white striped patterns at predetermined intervals in the rotational direction of the disc and the striped patterns are irradiated by light of a discharge tube which is turned on and off at the frequency of a particular musical sound. When the striped patterns are seen as if stopped, it is judged that the sound is correct. The 12 windows respectively correspond to the notes C to B of one octave and have formed thereon striped patterns arranged in integral multiple relationships, with which tuning of notes of different octaves is achieved.
This type of tuner is so constructed as to drive the plurality of discs with one motor, and hence has such disadvantages as complexity in construction and expensiveness.
In a modified form of this type of tuner, the number of windows are reduced to one and instead the number of revolutions of the motor is changed by a changeover switch in a stairstep manner in accordance with each particular note, thereby changing the strobe frequency. In some cases, a cathode ray tube is employed as the indicating means. Namely, on the screen of the cathode ray tube, a strip-like bright line is normally displayed at a sweep speed of the frequency corresponding to each note. An electron beam is brightness modulated by the sound given off by a musical instrument and when the frequency of the sound is synchronized with the sweep speed defined by the switch, the bright line becomes a broken line and is seen as if stopped. When the frequency of the musical sound is a little deviated from the defined frequency, the broken line moves to right or left. Depending upon whether the broken line moves to right or left, it is judged whether the frequency of the musical sound is deviated upwardly or downwardly. However, this type of tuner employs the cathode ray tube, and hence is expensive.
Another conventional type of tuner employs a lamp as the indicating means so as to reduce the manufacturing cost. In this tuner, a plurality of lamps are aligned in line and normally turned on and off one after another at high speed, that is scanned in such a manner as if they are all lighted simultaneously. When a musical sound is given forth, if its frequency is equal to the scanning speed selected by a changeover switch, only one lamp, for example, the center one is lighted. Where the frequency of the musical sound is deviated upwardly or downwardly, the lamps are lighted in a sequential order from right to left or left to right and the direction of the lighting indicates the direction of the frequency deviation. This tuner has an advantage of low manufacturing cost.
With these conventional tuners, however, the direction of the frequency deviation is indicated first and, in order to detect the amount of frequency deviation, it is necessary, for example, in the case of the tuner employing the strobe disc, to adjust a motor speed adjusting knob until the striped pattern of the window corresponding to the note of the musical sound stops and then to read a rotary scale of the knob. In the case of the tuner employing the cathode ray tube, too, it is necessary to adjust a sweep speed fine control knob to stop the displayed broken line. And, also in the case of the tuner using the lamps, it is required to adjust a lamp switching speed adjusting knob to stop the lamp lighting position at the center.
In the practical tuning of a musical instrument, the player is required to tune the instrument in accordance with the amount of the frequency deviation obtained by himself while handling the instrument at the same time. Consequently, it is inconvenient for him to adjust the adjusting knobs, too. Further, in the case of musical sounds of high frequencies, the frequency difference is likely to be large, so that, if such a sound is out of tone, the flow of the striped pattern of the strobe disc, the broken line displayed on the cathode ray tube or the lamp indication is very fast and the direction of the frequency deviation is difficult to judge. In the case of low-frequency sounds, the frequency difference is not so large, and consequently even if such a sound is not correct, the flow of the striped pattern of the strobe disc, the broken line on the cathode ray tube or the lamp indication is slow, and hence its indication cannot be recognized immediately.
One object of this invention is to provide an electronic tuner which is adapted for a direct-reading indication of the amount of frequency deviation of a musical sound.
Another object of this invention is to provide an electronic tuner which furnishes a direct-reading indication of the amount of frequency deviation of a musical sound requiring the player only to produce the sound from his musical instrument.
Another object of this invention is to provide an electronic tuner which is designed to indicate the ratio between the frequency of a musical sound and that of a reference oscillator and wherein, whether the frequency of the sound is high or low, the amount of deviation can be directly indicated by a scale graduated in percent.
Another object of this invention is to provide an electronic tuner which employs a switch for changing over the oscillation frequency of a reference oscillator to the frequencies of each scale, and hence enables tuning for 12 notes of each scale.
Another object of this invention is to provide an electronic tuner in which higher harmonics that are an even-number times a reference signal supplied to a phase comparator are superimposed upon the reference signal to enable tuning at one set position for each particular note of several octaves.
Another object of this invention is to provide an electronic tuner which is capable of correctly indicating the frequency of a musical sound even if the oscillation frequency of a reference oscillator drifts due to a temperature change or the like.
Another object of this invention is to provide an electronic tuner which is capable of selectively changing a standard frequency for tuning to 440, 435 and 445Hz.
Still another object of this invention is to provide an electronic tuner which employs digital indicating means to facilitate the reading of an indication.